When using electronic equipment on rail vehicles it was generally necessary to shelter the various components of the electronic equipment from environmental pollution by dust or projected water. However, by sheltering or enclosing the electronic components completely within a housing, the cooling of the electronic components became more difficult.
A prior art arrangement for cooling electronic power equipment such as power semiconductors was developed wherein the power semiconductors were directly immersed in FREON in a sealed container without pumps or cooling fans. This prior art arrangement is disclosed in a paper entitled "Two Phase FREON Cooling for Electronic Power Equipment" presented at proceedings of the International Conference on Advanced Propulsion Systems for Urban Rail Vehicles, February 1980, which was sponsored by the U.S. Department of Transportation, Urban Mass Transportation Administration and coordinated by the MITRE Corporation of McLean, Virginia. Although the semiconductors are completely immersed in the liquid FREON the container is not completely filled with liquid FREON and is partially filled with FREON vapor. Thus, the heat produced by the semiconductors causes the liquid FREON surrounding the semiconductors to vaporize and rise to the surface of the liquid FREON in the form of bubbles. The heat is then transferred from the cylinder to the atmosphere by means of a plurality of fins protruding outwardly from the container. As the FREON vapor is cooled the FREON will condense on the inner wall of the container and flow back into the liquid FREON. The returning coolant is agitated by the turbulant action of the ascending bubbles so that part of the heat produced by the semiconductor is transferred by convection of the liquid coolant to the area of the inner wall of the container which is in contact with the liquid coolant and is dissipated to the exterior of the container through the container wall. However, in such a prior art arrangement, the agitation of the liquid coolant by the turbulant action of the ascending bubbles is erratic and the coefficient of heat transfer by convection is so small that only a small part of the heat is dissipated by convection heat transfer.